The use of pesticides in agriculture makes it possible to plant extensive mono cultures and often leads to substantial yield increases of food and feed crops. Demand and application have grown steadily over the years, leading to increased contamination of the soil due to the toxic nature of pesticides. Soils save the toxins and their decomposition products so that wildlife is also affected by them. Among the undesired side effects are damages to useful plants and insects like bees. The wind carries pesticides to uncontaminated areas such as fields used for organic farming. Rain also transports the chemicals away from their original area of application to waters and groundwater. Although in most cases the limit values for particular pesticides and their decomposition products are not exceeded, the cumulative effect on humans and animals has not been thoroughly investigated so far. The possible accumulation of pesticides in the food chain could be a source of health hazards; therefore strict quality control of soils is indispensable.